#include <iostream>
int gcd(int a, int b);
int main()
{
int a = 12, b = 20;
int _gcd = gcd(a, b);
std::cout << "The GCD (greatest common divisor) of " << a << " and " << b << " is: " << _gcd;
}
int gcd(int a, int b) {
return b == 0 ? a : gcd(b, a % b);
}
/*
run:
The GCD (greatest common divisor) of 12 and 20 is: 4
*/